Hello, Tying to exchange message on ssh server but not completed anyhow due to issue on TCP level. Could any body help me out why there no message exchanged after "TCP Previous segment lost"? Please find the Wireshark file at - https://www.cloudshark.org/captures/6c6df098b205 Thanks in advanced :) asked 07 Sep '15, 03:24  sammi edited 07 Sep '15, 03:34 |
One Answer:
The trace taken at the server shows that the first 'full-MSS' segment from the client (tcp.seq==1717) that contained 1448 (not 1148 as initially posted] bytes did not make it to your server. Your server sends an ACK with tcp.ack==1717 asking for the segment that is missing but it never arrives (most probably because the retransmitted packets suffer the same death). You can try a ping to find out what maximum size goes through your infrastructure unfragmented. Regards Matthias answered 07 Sep '15, 04:30  mrEEde edited 12 Sep '15, 07:56 |
Hi Matthias,
Could you please elaborate more because I didn't found 1148 bytes in trace for (tcp.seq==1717)? My colleague wants a reason to change the MTU size.
Thanks in advanced !
Regards, Sammi
@mrEEde, 1448 bytes are missing, not 1148. @sammi, look at the relative seq number of packet 61 (1717) and packet 62 (3165), then you will understand why 1448. Do the ping test before changing the MTU.
Roland's right, the negotiated MSS is 1448 , well spotted!
The negociated MSS is 1460. The missing packet had 1448 bytes of data.
A MSS of 1460 with negotiated timestamps option results in a net segment size of 1448 ...